A typical design document for something like the F-1, though, was produced under intense deadline pressure and lacked even the barest forms of computerized design aids. Such a document simply cannot tell the entire story of the hardware. Each F-1 engine was uniquely built by hand, and each has its own undocumented quirks. In addition, the design process used in the 1960s was necessarily iterative: engineers would design a component, fabricate it, test it, and see how it performed. Then they would modify the design, build the new version, and test it again. This would continue until the design was “good enough.”
Lots of parallels with software development and reverse engineering.